Swift中如何将自定义类对象添加到数组？解决append方法调用不匹配报错

咱们先来理清报错的核心原因：你现在调用friendsList.append("John", "Doe", 20)的时候，是直接把三个零散的参数扔给了append方法，但friendsList是[Friend]类型的数组——它只接受Friend类的实例作为append的参数，根本不认识这三个单独的字符串和数字呀！

那正确的做法其实很简单，分两步走：

1. 先通过Friend的初始化方法，创建出一个个Friend类型的对象实例；
2. 再把这些实例逐个添加到friendsList数组里。

完整的修正代码示例 #

import UIKit 
class ViewController: UIViewController { 
    var friendsList: [Friend] = [] 
    override func viewDidLoad() { 
        super.viewDidLoad() 
        // 实例化5个Friend对象并添加到数组
        let friend1 = Friend(firstname: "John", lastname: "Doe", age: 20)
        friendsList.append(friend1)
        
        let friend2 = Friend(firstname: "Jane", lastname: "Smith", age: 22)
        friendsList.append(friend2)
        
        let friend3 = Friend(firstname: "Mike", lastname: "Brown", age: 19)
        friendsList.append(friend3)
        
        let friend4 = Friend(firstname: "Lisa", lastname: "Miller", age: 21)
        friendsList.append(friend4)
        
        let friend5 = Friend(firstname: "Tom", lastname: "Wilson", age: 23)
        friendsList.append(friend5)
    } 
}

更简洁的写法 #

如果你不想单独声明每个friend变量，也可以直接在append方法里创建实例，代码会更紧凑：

override func viewDidLoad() { 
    super.viewDidLoad() 
    friendsList.append(Friend(firstname: "John", lastname: "Doe", age: 20))
    friendsList.append(Friend(firstname: "Jane", lastname: "Smith", age: 22))
    friendsList.append(Friend(firstname: "Mike", lastname: "Brown", age: 19))
    friendsList.append(Friend(firstname: "Lisa", lastname: "Miller", age: 21))
    friendsList.append(Friend(firstname: "Tom", lastname: "Wilson", age: 23))
}

这样写之后，Swift就不会再报错啦，因为你现在传给append的是一个个符合数组类型要求的Friend实例~

内容的提问来源于stack exchange，提问作者Shuran Gong